Rescue teams in Lebanon are searching rubble for dozens of people missing a day after a huge explosion devastated the port area of the capital, Beirut.

The explosion, which shook the whole city, killed at least 113 people and injured more than 4,000 others. A two-week state of emergency has been declared.

Lebanon’s President Michel Aoun said the blast was caused by 2,750 tonnes of ammonium nitrate stored unsafely in a warehouse.

All port officials have been put under house arrest pending an investigation.

According to local media, customs chief Badri Daher claims his agency had repeatedly called for the ammonium nitrate to be removed, but “this did not happen, and we leave it to the experts to determine the reasons”.

Ammonium nitrate is used as a fertilizer in agriculture and as an explosive.

Opening an emergency cabinet meeting, President Aoun said: “No words can describe the horror that has hit Beirut last night, turning it into a disaster-stricken city.”

The blast occurred just after 18:00 on August 4 after a fire at the port, and it was felt 150 miles away on the island of Cyprus, in the eastern Mediterranean.

Security forces have sealed off a wide area around the blast site, and rescuer workers have been looking for bodies and survivors under rubble while boats searched the waters off the coast.

However, the overnight rescue effort was hampered by a lack of electricity.

Public Health Minister Hamad Hassan said the country’s health sector was short of beds and lacked the equipment necessary to treat the injured and care for patients in critical condition.

He said a “large number of children” had been rescued but added that he feared that the number of dead would rise further.

The Saint Georges hospital near the site of the blast was badly damaged and several members of staff were killed. Three Beirut hospitals were closed with two others only partially operational, the World Health Organization (WHO) said. The WHO said it would airlift medical supplies to Lebanon on August 5.

Three French planes are due to arrive carrying 55 rescuers, medical equipment and a mobile clinic equipped to treat 500 people. French President Emmanuel Macron will visit on August 6. The EU is sending 100 firefighters with vehicles, dogs and equipment. Russia is sending five planes carrying rescuers, doctors and equipment.

According to Beirut’s governor Marwan Aboud, many buildings and homes have been reduced to an uninhabitable mess of glass and as many as 300,000 people have been left homeless.

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The ammonium nitrate had reportedly been in a warehouse in Beirut port for six years after it was unloaded from a ship impounded at the port in 2013.

The head of Beirut port and the head of the customs authority both told local media that they had written to the judiciary several times asking that the chemical be exported or sold on to ensure port safety.

The port’s General Manager Hassan Koraytem told OTV that they had been aware that the material was dangerous when a court first ordered it stored in the warehouse, “but not to this degree”.

Lebanon’s Supreme Defense Council has vowed that those found responsible will face the “maximum punishment” possible.

The ammonium nitrate arrived on a Moldovan-flagged ship, the Rhosus, which entered Beirut port after suffering technical problems during its voyage from Georgia to Mozambique, according to Shiparrested.com, which deals with shipping-related legal cases.

The Rhosus was inspected, banned from leaving and was shortly afterwards abandoned by its owners, sparking several legal claims. Its cargo was then removed and stored in a port warehouse for safety reasons, the report said.